1. Industrial Field of the Invention
The present invention relates to a magneto-resistance effect element for thin film heads or magnetic field sensors.
2. Prior Art
There have conventionally been conducted developments of a magnetic resistance sensor (hereinafter referred to as an MR sensor) and a magnetic resistance head (hereinafter referred to as an MR head) in which magnetic resistance elements are employed, and Permalloy of Ni.sub.0.8 Fe.sub.0.2 has been mainly used as a magnetic material applied to them. In the case of this material, however, the MR (magnetic resistance) ratio (hereinafter referred to as .DELTA.R/R) is about 2.5%, and consequently, a material having a larger .DELTA.R/R is required to obtain a magnetic resistance element of higher sensitivity. Recently, it was discovered that a giant magnetoresistance effect is induced by an artificial superlattice film made of a thin film containing Fe and Cr (see Physical Review Letter, vol. 61, p. 2472, 1988). In the case of this material, however, a large .DELTA.R/R can not be obtained unless an intense magnetic field of 10 kOe or more is applied to it, which results in a problem in practicability.